DGWG session, Caltech general Meeting, BK*nn vs HAD tag: impact of bwd EMC and fwd PID Elisa Manoni INFN Sez. Perugia DGWG session, Caltech general Meeting, December 14, 2010
Outline DG configurations and samples from September production impact of fwd PID in Breco and Breco+Bsig selection efficiencies impact of bwd EMC used as a veto impact of material in front of Fwd EMC
Detector geometries DG_4 : SVT_L0 + fwd TOF+ bwd EMC offline can study: impact of fwd PID, impact of bwd EMC DG_4a : as DG_4 but TOF made if Air (0-thickness TOF) comparing with DG_4 , study impact of TOF material in front of the EMC 3 3
Sample used 2010_September production, FastSim release V0.2.5, revs 307 and 311
Analysis strategy Baseline analysis impact of Fwd TOF: DG_4_allbkgs with Fwd TOF on and Bwd EMC off Kaons form Bsig and Breco: likelihood based selectors TightLHKaonfTOFSelection impact of Fwd TOF: DG_4_allbkgs with Fwd TOF off and Bwd EMC off Kaons form Bsig and Breco: likelihood based selectors TightLHKaonSelection impact of Bwd EMC: DG_4_allbkgs with Fwd TOF switched on and Bwd EMC switched on cut on Eextra deposited in bwd EMC (+ usual cut on Eextra from Barrel+Fwd) impact of material in front of Fwd EMC DG_4a_nopairs with Fwd TOF switched on and Bwd EMC switched off evaluate p0 mass and g energy resolutions and compare with DG_4
Impact of Fwd PID DG_4, cocktail + signal (all backgrounds)
Reco side kaon angular distribution B+K*+nn signal MC - true value - reco value, DCH+ TOF - reco value DCH CM LAB B+B- cocktail CM LAB
Reco side kaon momentum and multiplicity fraction of kaons in the Fwd region (q = [15°,25°]) : 5-7% efficiency gain depend on kaon momentum spectrum and multiplicity - DCH+TOF - DCH
B0K*0(K+p-)nn: Cut flow efficiency efficiency on Breco reconstr. and sel. normalized to # of gen evts efficiency on Bsig reconstr. normalized to # of sel Breco events totalsel efficiency normalized to # of gen evts signal sample relative efficiency gain (de/e) flow efficiency flow (%) - DCH+TOF - DCH
B+K*+(K+p0)nn: Cut flow efficiency efficiency on Breco reconstr. and sel. normalized t o# of gen evts efficiency on Bsig reconstr. normalized to # of sel Breco events totalsel efficiency normalized to # of gen evts signal sample relative efficiency gain (de/e) flow efficiency flow (%) - DCH+TOF - DCH
B+K*+(KSp+)nn: Cut flow efficiency efficiency on Breco reconstr. and sel. normalized to # of gen evts efficiency on Bsig reconstr. normalized to # of sel Breco events total sel efficiency normalized to # of gen evts signal sample relative efficiency gain (de/e) flow efficiency flow (%) - DCH+TOF - DCH
Remarks on Kp0 vs Kp Signal side Kaon momentum, before PID requirements high gain in Kp0 sample due to “low” DCH efficiency wrt to TOF - Kp - Kp0 DCH DCH+TOF
Remarks on Ksp After Breco sel. + Bsig mode reconstr. : Kpi: nTOF+DCH – nDCH = 45 Ksp: nTOF+DCH – nDCH = 10 After Breco+Bsig sel. : Kpi: nTOF+DCH – nDCH = 19 (42% of gained events falls in the signla box) Ksp: nTOF+DCH – nDCH = 7 (70% of “gained” events falls in the signal box) most of the Kspi events gained with TOF (i.e. higher Breco reconstruction) survive the full selection full selection efficiency gain higher than Breco efficiency gain
Impact of Bwd EMC DG_4 cocktail + signal (no pairs)
Eextra distributions : barrel + forward minimum gamma energy = 30 MeV signal MC BB cocktail Kp Kp0 Ksp
Eextra distributions : backward minimum gamma energy = 30 MeV signal MC BB cocktail Kp Kp0 Ksp
Eextra_bwd cut: optimization Strategy: scan the region Eextra_Bwd ∈ [0.05,0.5] GeV and compute FOM = S/sqrt(B) optimal cut ↔ maximum FOM Ksp B0K*0nn Kp B+K*+(K+p0)nn
Eextra_bwd cut: results EextraBwd < 0.05 GeV:
Impact of material in front of fwd EMC DG_4a cocktail + signal
p0 and g reconstruction more on p0 mass resolution and gamma energy resolution @ tomorrow EMC session
Impact on physics results (I) Eextra barrel + forward distributions, before Eextra cut Kp minimum gamma energy = 30 MeV DG_4 signal MC DG_4a signal MC Kp0 Ksp
Impact on physics results (II) DG_4 signal MC DG_4a signal MC cut flow efficiency: DG_4 and DG_4a consistent within statistical error
Conclusions
Conclusion DG studies performed using September_2010 Production FWD PID: gain on Breco reconstruction around 3% gain when applying PID requirements on the signal side around 2-4% total gain is expected to be 3% + 2-4% but selection cuts reduce the overall gain (some sanity check needed) BWD EMC preliminary studies indicates a 10% enhancement in the FOM when applying the Eextra_bwd cut EFFECT OF MATERIAL IN FRONT OF FWD EMC 1.5% loss in p0 efficiency reconstruction, gamma reconstruction efficiency almost unchanged physics performances doesn’t seem to change on signal MC more will be discussed at tomorrow EMC session
Back-up slides
PacHadRecoilUser code SemiExclusive reconstruction of Hadronic B modes limit the number of reconstructed Breco channels reconstruct only modes with purity >50% generate ad-hoc BB cocktail sample instead of generic Available Bsig modes K* K , Ks() , with e, , , (0), a1()